UV-Induced Antibacterial Activity of Green-Synthesized TiO2 Nanoparticles for the Potential Reuse of Raw Surface and Underground Water

The pollution of raw surface and underground water with pharmaceutical compounds has an impact on increasing the resistance of pathogenic microorganisms. Environmental challenges include investigating a novel and cost-effective therapeutic approach for the bactericidal treatment of water supplies. Ethyl acetate extracts from three marine algae (Caulerpa racemosa, Codium fragile, and Cystoseira myrica) obtained from the Red Sea (Hurghada, Egypt) were used for the green synthesis of TiO2 nanoparticles (TiO2-NPs). A highly crystalline nanoparticle structure with a stable tetragonal anatase structure was obtained; the mean concentrations were 2.43 to 6.09 x 10(8) NPs/mL and the average particle size was 125-131 nm. In ultrapure water, the TiO2-NPs were confirmed to be a stable solution following zeta potential analysis. UV light (lambda = 350 nm) for 2 h was used to activate the TiO2-NPs before the antibacterial activity tests. The application of UV-activated TiO2-NPs for 4 h treatments demonstrated promising bactericidal activity, with a 73.08% reduction in Salmonella typhi and a 91.51% reduction in Enterobacter ludwigii. Antibiofilm activities against the reference strains Salmonella typhi NCTC 12023/ATTC and Morganella morganii ATCC25829 and the bacterial isolates Klebsiella pneumoniae, Enterobacter ludwigii, and Enterococcus faecium were tested. The TiO2-NPs were nontoxic against the human normal cell line RPE1. Regarding the treatment of total and fecal coliform, in addition to fecal streptococci, in raw surface and underground water, the UV-activated TiO2-NPs prepared from the ethyl acetate extracts of Caulerpa racemosa showed high applicability. The present study offered insights into the nature and development of nontoxic and green TiO2-NP formulations for use as modern antibacterial alternatives against coliforms in aquatic systems.

Automated summary

The research demonstrates that TiO2 nanoparticles synthesized using extracts from marine algae exhibit significant antibacterial activity against microorganisms such as Salmonella typhi and Enterobacter ludwigii after UV activation, while being non-toxic to human cells. Furthermore, in the treatment of coli-form bacteria in surface and underground water, the TiO2 nanoparticles show high applicability, suggesting their potential as modern antibacterial alternatives.